High-pressure fuel injection system for diesel engine

ABSTRACT

A high-pressure fuel injection system for a diesel engine including a plurality of main pumps for injecting fuel each located at one of cylinders of the engine and formed with a fuel injection port, a metering and distributing pump formed with fuel discharge ports corresponding in number to the cylinders of the engine for discharging fuel to be injected in timed relation to the rotation of the engine, a plurality of injected fuel metering valves for metering the fuel to be injected before introduction into the metering and distributing pump, a plurality of pipes for fluidly connecting each of the main pumps for injecting fuel with each other discharge ports of the metering and distributing pump, and an actuating mechanism connecting the engine with each of the main pumps for injecting fuel to actuate each of the main fuel injection pump for injecting fuel in timed relation to the rotation of the engine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to high-pressure fuel injection systems fordiesel engines, and more particularly it is concerned with ahigh-pressure fuel injection system for a diesel engine havingpressurized injection means associated with each cylinder of the engine.

2. Description of the Prior Art

In a fuel supply system for a diesel engine, it is the amount of theinjected fuel and injection timing that exert great influences on theperformance of the engine.

Attempts have been made to optimize control of these two factors byutilizing electronic control techniques, to achieve improved results incontrolling them. Methods of effecting control along these lines aredisclosed in Japanese Patent Application Laid-Open No. 60851/81 and No.56660/82, for example.

Even if electronic control techniques are utilized, some problems wouldbe raised when a section of the fuel injection system for compressingthe fuel and a section thereof for injecting it are spaced apart a greatdistance from each other. For example, a time lag caused by the movementof the fuel between the two sections and the behavior of pressure waveswould make it impossible to accurately effect control of the amount ofthe injected fuel and injection timing.

SUMMARY OF THE INVENTION Object of the Invention

This invention has as its object the provision of a high-pressure fuelinjection system for a diesel engine suitable for utilizing electroniccontrol techniques which is capable of avoiding a deterioration in theaccuracy and precision with which control of injection timing iseffected which might otherwise be caused to occur by a lag in time ofthe fuel flow in the fuel injecting section behind the fuel flow in thefuel compressing section.

STATEMENT OF THE INVENTION

The outstanding characteristics of the invention are that a control unitfor deciding upon the amount of the injected fuel and injection timingis constructed as a single system and the two volumes of fuel decided bythe control unit are distributed to the compressing section of eachcylinder so as to decide not only the amount of the injected fuel butalso the injection timing based on the two volumes of the fuel, and thatthe two volumes of the fuel for deciding the amount of the injected fueland injection timing are transferred to the compressing sections of allthe cylinders by means of a pressurizing and distributing pump which iscommonly shared by the cylinders.

More specifically, means for controlling the amount of the injected fueland injection timing feed the two volumes of fuel which serve therespective purposes to the pressurizing and distributing pump whichadmits them to two separate chambers respectively and pressurizes themtherein. The two volumes of fuel thus pressurized are successively fedin an orderly manner to two chambers formed in the compressing andinjecting section of each cylinder to decide the amount of the injectedfuel and injection timing respectively. They are fed to the cylinder ata time when no injection takes place therein in conformity with theorder of combustion taking place in the cylinders.

In the compressing section of each cylinder, the desired amount ofinjected fuel and injection timing can be decided merely by applyingmechanical pressure to the fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a systematic view of the high-pressure fuel injection systemcomprising one embodiment of the invention;

FIG. 2 is a sectional view of the metering and distributing pump;

FIG. 3 is a sectional view taken along the line III--III in FIG. 2, inexplanation of the compression cam;

FIG. 4 is a sectional view taken along the line IV--IV in FIG. 2,showing the control section of the metering and distributing pump;

FIG. 5 is a sectional view taken along the line V--V in FIG. 2, showingthe discharge section of the metering and distributing pump;

FIG. 6 is a sectional view of the main pump, showing its construction;and

FIG. 7 is a fragmentary enlarged view of the roller and roller shoeshown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a systematic view of one embodiment of the fuel injectionsystem in conformity with the invention, in which a metering anddistributing pump 100 and cams 103a-103d are driven for rotation by adrive shaft 102 of an engine. The metering and distributing pump 100draws fuel by suction from a fuel tank 101 through a suction line 112 bymeans of a built-in feed pump, and pressurizes the fuel to a pressure ofseveral kg/cm². Two solenoid valves 15 and 16 controlled by commandsfrom a control unit 300 decide upon two volumes of fuel which arepressurized by the metering and distributing pump 100 and fed into themain pumps 200a-200d via timing pipes 104 and volume regulating pipes105 at a pressure of several to several scores of atmospheric pressures.The main pumps 200a-200d are compressed in time relation to injectionsof fuel into the engine by rocker arms 111a-111d supported at pivots110a-110b via connecting rods 109a-109d actuated by cams 103a-103drespectively.

The injection timing is decided by the volume of fuel fed via the timingpipes 104, and the amount of the injected fuel is decided by the volumeof fuel fed via the volume regulating pipes 105. The main pumps200a-200d are located in the vicinity of the respective cylindersassociated therewith.

The fuel overflowing the main pumps 200a-200d and the fuel dischargedfrom the metering and distributing pump 100 because of being cooled andother reasons flow through overflow lines 106a-106d and an oil dischargeline 107 respectively to a return pipe 108 through which the fuel flowsto the fuel tank 101.

Various sections of the system will now be described in detail. FIG. 2is a vertical sectional view of one constructional form of metering anddistributing pump 100 in conformity with the invention. The functionalobject of the metering and distributing pump 100 is to decide, byseparate means for controlling the amount of the injected fuel andinjection timing respectively, two volumes of fuel fed to the main pumpsof the cylinders and to transfer the two volumes of fuel to the mainpumps after suitably pressurizing them.

Referring to FIGS. 2-5, the metering and distributing pump 100 comprisesa rotor 1 driven for rotation by the drive shaft 102 shown in FIG. 1rotating in synchronism with the engine. The rotor 1 has mounted at oneend portion thereof a pair of plungers 2 fitted in a radial bore, and aroller shoe 8 and a roller 9 located on the outside of each plunger 2.The plungers, roller shoes 8 and rollers 9 rotate with the rotor as aunit.

A cam ring 3 having on its inner peripheral surface four cams 3A ofdifferent shapes is supported by a housing 10 and located in such amanner that the cams 3A are kept in contact with the outer peripheralsurfaces of the rollers 9. The rotor 1 rotates while being maintained incontact with an inner peripheral surface of a sleeve 42 supported by asleeve holder 41 secured to the housing 10.

The rotor 1 is formed therein with a first pressurizing chamber 4 and asecond pressurizing chamber 6. The first pressurizing chamber 4 islocated between the two plungers 2 disposed for sliding movement in theradial bore in face-to-face relation on the left side of the rotor 1 asseen in FIG. 2 and a left end face of a free piston 5 fitted in an axialcenter bore, and the second pressurizing chamber 6 is located between aright end face of the free piston 5 and a stopper 7 secured to a rightend of the axial center bore to avoid fuel leaks.

The plungers 2, roller shoes 8, rollers 9 and cam ring 3 constitute apressurizing mechanism, which is maintained in communication with thefirst pressurizing chamber 4.

The first pressurizing chamber 4 is selectively brought intocommunication with a first discharge passage 29 located radially of therotor 1 depending on the position of the free piston 5. The secondpressurizing chamber 6 is maintained in communication with a seconddischarge passage 23 located radially of the rotor 1.

Referring to FIG. 3, the pressurizing mechanism built in the rotor 1 hasa suction period θ₁ in which suction of fuel is effected and acompression period θ₂ in which compression and discharge of the fuel areeffected which alternately take place as the rotor 1 rotates. FIG. 3shows the invention as incorporated in a metering and distributing pumpof a four-cylinder engine, in which the four cams 3A of different shapeseach corresponding to one of the four cylinders are located in one offour equally divided portions of the inner peripheral surface of the camring 3. As subsequently to be described, the suction period θ₁ andcompression period θ₂ are determined by the shapes of the cams 3A of thecam ring 3 and the volume of liquid (fuel) drawn by suction into thefirst pressurizing chamber 4.

Referring to FIG. 2 again, the metering and distributing pump 100 showntherein is in a condition in which the compression period has finishedor the suction period has just begun. In this condition, the free piston5 of the pump 100 has moved rightwardly a substantial distance to allowthe first pressurizing chamber 4 to communicate with the first dischargepassage 29 located radially in the rotor 1 as described hereinabove.

Referring to FIGS. 2-5 in which the pressurizing mechanism is in thesuction period, one of a plurality of first radial passages 11 equal innumber to the cylinders of the engine (four in this embodiment) whichextend radially outwardly from the first pressurizing chamber 4communicates with a first fixed passage 13 formed in the sleeve 42, andone of a plurality of second radial passages 12 equal in number to thecylinders of the engine (four in this embodiment) which extend radiallyoutwardly from the second pressurizing chamber 6 communicates with asecond fixed passage 14 formed in the sleeve 42. The first fixed passage13 and second fixed passage 14 are closed at ends thereof by armatures17 of a first solenoid valve 15 and a second solenoid valve 16respectively.

The solenoid valves 15 and 16 which are substantially of the sameconstruction are each contained in a case 18 in such a manner that thearmature 17 is movable vertically in the plane of the figure. Thevertical movement of the armature 17 is obtained by turning on and offthe respective solenoid valves 15 and 16.

The solenoid valves 15 and 16 each have a coil 19, a fixed magnetic pole20 and a spring 21 mounted between the fixed magnetic pole 20 andarmature 17. The spring 21 normally (when the solenoid valves 15 and 16are in OFF position) urges the armature 17 to move downwardly in thefigure by its biasing force, to keep the valves 15 and 16 closed.

In the solenoid valves 15 and 16, the coil 19 is energized as a currentis passed thereto from a terminal 22 to form a magnetic path connectingthe fixed magnetic pole 20, case 18 and armature 17 together. Thearmature 17 moves upwardly by overcoming the biasing force of the spring21, to open the valves 15 and 16. As the valves 15 and 16 are opened,end portions of the first fixed passage 13 and second fixed passage 14are released. It is not essential that the valve opening timing for thesolenoid valve 15 match that for the solenoid valve 16. However, whenthe solenoid valves 15 and 16 are opened, fuel pressurized to a suitablepressure level by a feed pump, not shown, driven by an electric motor oran engine, not shown, is fed through the first fixed passage 13 andsecond fixed passage 14 to the first pressurizing chamber 4 and secondpressurizing chamber 6 via the first radial passage 11 and second radialpassage 12 which are indexed with the two chambers 4 and 6 respectively(suction).

A section taken along a plane V--V including the first discharge passage29 and a section taken along a plane V--V including the second dischargepassage 23 in FIG. 2 are substantially similar to each other. In FIG. 5,parts indicated by reference numerals disposed in a section includingthe second discharge passage 23 are shown.

The first discharge passage 29 formed in the rotor 1 is brought intocommunication with one of a plurality of first output passages 30 (inthis embodiment, four first output passages 30 equal in number to thecylinders are disposed radially in positions equidistantly spaced apartfrom each other) formed in the sleeve 42 when they are indexed with eachother, and with one of connecting ports 31 formed in the sleeve holder41. The timing pipes 104 shown in FIG. 1 are each connected with one ofthe connecting ports 31. Likewise, the second discharge passage 23formed in the rotor 1 is brought into communication with one of aplurality of second output passages 24 (in this embodiment, four secondoutput passages 24 equal in number to the cylinders are disposedradially in positions equidistantly spaced apart from each other) formedin the sleeve 42 when they are indexed with each other, and with one ofconnecting ports 25 formed in the sleeve holder 41. The volumeregulating pipes 105 shown in FIG. 1 are each connected with one of theconnecting ports 25.

The solenoid valves 15 and 16 are connected at their upstream ends witha fuel supply port 43 to feed fuel pressurized to a predeterminedpressure level to each of the first pressurizing chamber 4 and secondpressurizing chamber 6 via the first fixed passage 13 and second fixedpassage 14 respectively, when each other solenoid valves 15 and 16 isopened.

A pulser 26 is mounted to a right end portion of the rotor 1 and rotatestherewith as a unit. A detector 27 is fixedly mounted to an outerperiphery of the pulser 26 to cooperate therewith. The pulser 26 anddetector 27 are similar to a rotating position detector of a contactlessignition system of a spark ignition type engine, for example, and supplyan electrical output signal to a detection terminal 28 when the rotor 1moves to a position corresponding to a fuel feed initiating time (thetime at which each of the solenoid valves 15 and 16 is opened and beginsto draw fuel by suction) in this embodiment.

Operation of controlling the volumes of fuel drawn by suction in thesuction period θ₁ shown in FIG. 3 will be described.

The electronic control unit 300 shown in FIG. 1 receives a signal fromthe detection terminal 28 indicating that the time for commencing thesuction period has been reached and opens the first solenoid valve 15and second solenoid valve 16, either simultaneously or with a time lag,immediately after receiving the signal from the terminal 28 or with asuitable delay. When the first solenoid valve 15 is opened, the fuelpressurized to a predetermined pressure level is fed through the fuelsupply port 43 into the first pressurizing chamber 4 via the first fixedpassage 13 and first radial passage 11. At this time, the rotor 1 hasrotated to a position in which the rollers 9 and roller shoes 8 are incontact with the cam 3A on the inner peripheral surface of the cam ring3 which is configured such that the movements of the rollers 9 androller shoes 8 are not suppressed (the suction period θ₁ shown in FIG.2), to allow the rollers 2 to move radially outwardly.

Thus, the fuel is fed into the first pressurizing chamber 4 in a volumewhich is decided by the period of time in which the solenoid valve 15 isopen, the dimensions of the passages and the difference between thepressure in the fuel supply port 43 and the pressure in the firstpressurizing chamber 4. That is, in spite of whether the system has acharacteristic such that the pressure in the supply port 43 is constantregardless of the rotational speed of the pump or varied depending onthe rotational speed of the pump, the characteristic is decided upon bytaking into consideration the influences exerted by centrifugal forcesacting on the plungers 2. However, in actual practice, it is possible tocontrol the volume of the fuel fed into the first pressurizing chamber 4based merely on the duration or period of time in which the firstsolenoid valve 15 remains open.

Likewise, as the second solenoid valve 16 is opened, it is possible tocontrol the volume of the fuel (liquid) fed into the second pressurizingchamber 6. The liquid (fuel) fed into the second pressurizing chamber 6causes the free piston 5 to shift leftwardly in FIG. 2 to increase thepressure in the first pressurizing chamber 4 and move the plungers 2radially outwardly. The system is constructed such that the leftwardmovement of the free piston 5 closes the first discharge passage 29.

In this way, the free piston 5 is caused to shift leftwardly in FIG. 2in conformity with the volume of the fuel (liquid) fed into the secondpressurizing chamber 6. The plungers 2 are moved radially outwardly adistance corresponding to the volume of the fuel fed into the secondpressurizing chamber 6 plus the volume of the fuel fed into the firstpressurizing chamber 4.

In the control operation described hereinabove, the pressurizingmechanism composed of the plungers 2, roller shoes 8 and rollers 9operates in such a manner that the suction period allowing the fuel toflow freely into the pressurizing chambers 4 and 6 exists.

Operation of controlling the volumes of the fuel discharged in thecompression period θ₂ will now be described.

In the compression period, as shown in FIG. 2, the rollers 9 and rollershoes 8 are in contact with the cam 3A configured such that they arepressed radially inwardly by the cam 3A, to move the plungers radiallyinwardly.

The first radial passage 11 and first fixed passage 13 maintained incommunication with each other and the second radial passage 12 andsecond fixed passage 14 maintained in communication with each other inthe suction period are brought out of communication with each other inthe compression period.

At the same time, the discharge passage 23 connected with the secondpressurizing chamber 6 is brought into communication with one of theoutput passages 24 (which are equal in number to the cylinders)connected with the respective connecting ports 25 (see FIG. 5). Thevolume regulating pipes 105 shown in FIG. 1 are connected at one endwith the respective connecting ports 25 and at the opposite end with themain pumps 200 of the respective cylinders. During the compressionperiod, the first discharge passage 29 connected with the firstpressurizing chamber 4 is closed by the free piston 5.

As the rotor 1 rotates, the cam 3A of the configuration restraining themovement of the rollers 9 and roller shoes 8 moves the plungers 2radially inwardly, to thereby compress the liquid (fuel) drawn bysuction into the first pressurizing chamber 4 and raise its pressure.

At the time when the fuel in the first pressurizing chamber 4 ispressurized and its pressure rises, the fuel in the second pressurizingchamber 6 is pressurized through the free piston 5 and its pressure alsorises, because the first discharge passage 29 is closed by the freepiston 5. The fuel in the second pressurizing chamber 6 thus pressurizedis fed via the second discharge passage 23, output passage 24 andconnecting port 25 to each of the main pumps 200.

As the fuel is discharged from the second pressurizing chamber 6, thefree piston 5 shifts rightwardly to the position shown in FIG. 2. Whenthe free piston 5 is in the position shown in FIG. 2, the firstdischarge passage 29 is connected with one of the output passages 30(equal in number to the cylinders), so that the fuel is fed into themain pumps 200 of the corresponding cylinders through the output passage30 and connecting port 31 to each of the main pumps 200 for thecylinders via the timing pipes 104 shown in FIG. 1.

As the rotor 1 further rotates and enters the next following suctionperiod, the free piston 5 shifts leftwardly a distance corresponding tothe volume of the fuel drawn by suction into the second pressurizingchamber 6. The liquid (fuel) drawn by suction into the secondpressurizing chamber 6 corresponds in volume to the fuel dischargedthrough the second discharge passage 23 in the next followingcompression period until the first discharge passage 29 is opened. Thus,by controlling the period of time in which the second solenoid valve 16is open, it is possible to transfer the volume of fuel drawn by suctioninto the second pressurizing chamber 6 to the main pump 200 through thevolume regulating pipe 105 in the compression period.

Meanwhile, by controlling the period of time in which the first solenoidvalve 15 is open, it is possible to transfer the volume of fuel drawn bysuction into the first pressurizing chamber 4 to each main pump 200 viathe timing pipe 104.

These volumes of fuel are used for deciding the final amount of the fuelinjected and injection timing subsequently to be described.

Referring to FIG. 3, the cam ring 3 which is fixed is formed on itsinner peripheral surface with portions of the cams 3A for deciding thesuction period θ₁ and the compression period θ₂ which are arrangedalternately. The portion of the cams 3A for the suction period θ₁ isconfigured such that the movement of the plungers 2, roller shoes 8 androllers 9 radially outwardly of the rotor 1 is not restrained, and theportion of the cams 3A for the compression period θ₂ is configured suchthat as the rotor 1, roller shoes 8 and rollers 9 rotate, they aregradually urged to move radially outwardly of the rotor 1, so that themovement of the plungers 2 radially inwardly of the rotor 1 pressurizedthe liquid in the first pressurizing chamber 4.

When the period of time in which the first solenoid valve 15 remainsopen is prolonged, the volume of the fuel fed into the firstpressurizing chamber 4 is great and the distance covered by the movementof the plungers 2 radially outwardly of the rotor 1 is great. Thus, theroller 9 are brought into contact with the cam 3A of the necessary shapeon the cam ring 3 earlier than would be the case if the distance weresmaller, and the compression period θ₂ starts earlier to allow the fuelto be compressed and transferred earlier than would be the case if thedistance were smaller. When the period of time in which the secondsolenoid valve 16 remains open is prolonged and the volume of the liquiddrawn by suction into the second pressurizing chamber 6 is great, thefree piston 5 is biased leftwardly, and the plungers 2 project radiallyoutwardly of the rotor 1 with the volume of the liquid drawn by suctioninto the first pressurizing chamber 4 remaining constant. Therefore, thecompression period θ₂ would begin earlier for the same reason asdescribed hereinabove.

Stated differently, the time at which transfer of the volumes of theliquid is commenced may vary depending on the volumes of the liquidtransferred through the timing pipes 104 and volume regulating pipes 105to the main pumps 200a-200d. This raises no problem for the enginebecause it takes place in other periods than the compression period θ₂of the corresponding main pump 200.

The main pumps 200a-200d will now be described by referring to FIG. 6.

Each main pump 200 comprises a body 201 mounted to one of the cylindersof the engine and having mounted therein a pressurizing body member 202sealed by a seal member 227, a shuttle body member 203, a discharge bodymember 204 and a nozzle body member 205. The nozzle body member 205 isdisposed in the body 201 in such a manner that it protrudes into acombustion chamber of the engine. The four body members 202, 203, 204and 205 are finished in such a manner that surfaces thereof maintainedin contact with each other are sufficiently flat to provide an oiltightseal therebetween. The pressurizing body member 202 is formed in itscentral portion with a vertical bore in which a main plunger 206 isfitted for vertical sliding movement in a manner to define apressurizing space 226 beneath the main plunger 206. The pressurizingspace 226 is maintained in communication with an upper space 214 formedin an upper portion of the shuttle body member 203, and a timing space229 formed as a timing connector 208 is threadably connected to theshuttle body member 203.

The shuttle body member 203 is formed with a center vertical bore forfitting therein a shuttle 207 for vertical sliding movement, and a lowerspace 215 is formed beneath the shuttle 207. The lower space 215 ismaintained in communication with a volume regulating space 230 formed asa volume regulating connector 209 is threadably connected to thedischarge body member 204, a high-pressure vertical bore 220, an anglingduct 219 formed in the nozzle body member 205 and an injection space231. Supported in a central portion of the nozzle body member 205 forsliding movement is a needle 216 which is forced against a seat 233 bythe biasing force of a spring 218 exerted thereon through a springreceiver 217. A space formed in the discharge body 204 for mounting thespring 218 is communicated with a discharge vertical bore 222 via adischarge horizontal bore 221. The center vertical bore formed in theshuttle body member 203 for supporting the shuttle 207 is communicatedwith the discharge vertical bore 222 via an overflow passage 223. Thedischarge vertical bore 222 is also communicated with a free space 225disposed in a manner to surround the center bore for supporting the mainplunger 206. The discharge vertical bore 222 is maintained incommunication with a discharge space 234 formed in the body 201.

All the spaces shown and described hereinabove are filled with fuel whenthe system is in operation.

An overflow connector 210 is threadably connected to the body 201 in amanner to communicate with the discharge space 234, and an overflow pipe106 shown in FIG. 1 is connected to the body 201 through the connector210. The timing connector 208 is connected to the body 201 in such amanner that it is communicated with the timing space 229, and the timingpipe 104 shown in FIG. 1 is connected to the body 201 through the timingconnector 208. The volume regulating pipe 105 shown in FIG. 1 isconnected to the body 201 through the volume regulating connector 209 insuch a manner that it is communicated with the volume regulating space230.

In each of the connectors 208, 209 and 210, a check valve 211 is mountedand a spring 212 is connected at one end to a locker 213 and at theother end to the valve in such a manner that the valve 211 is biased bythe spring 212 into engagement with an opening of an inner passage ofthe connector to allow the liquid to flow therethrough only in onedirection. The connectors 208 and 209 are sealed by a seal member 228with respect to the body 201, and allow the liquid to flow from outsideinto the main pump 200. The connector 210 allows the liquid to flow fromthe main pump 200 to outside.

Operation of the main pump 200 of the aforesaid construction will now bedescribed. As described hereinabove, the volume of fuel which is to befinally injected into the cylinder flows into the volume regulatingspace 230 through the volume regulating pipe 105 and volume regulatingconnector 210 by opening the check valve 211. The volume of fuel furtherflows into the lower space 215 and forces the shuttle 207 to moveupwardly because the main plunger 206 is not restrained by the cam 103,connecting rod 109 and rocker arm 111. Thus, the fuel contained in theupper space 214 and pressurizing space 226 is also pressurized, topressurize the fuel in the timing space 229 communicated with thepressurizing space 226.

As described hereinabove, inflow of the fuel through the timing pipe 104and timing connector 108 into the body 201 takes place after inflow ofthe fuel through the volume regulating connector 209 is terminated. Thecheck valve 211 in the timing connector 208 avoids outflow of the fuelfrom the body 201 to outside, and the plunger 206 which is notrestrained moves upwardly a distance corresponding to the distancecovered by the upward movement of the shuttle 207 which closes theoverflow passage 223 by its outer periphery. Then, the inflow of thefuel through the volume regulating connector 209 is terminated, and theinflow of the fuel through the timing connector 208 is commenced.

The fuel which forces the check valve 211 in the timing connector 208 tomove to an open position flows into the pressurizing chamber 226 via thetiming space 229 and upper space 214. The pressure of the fuel acts onthe shuttle 207. However, since the check valve 211 in the volumeregulating connector 209 communicated with a lower portion of theshuttle 207 is closed and the pressure is not high enough to move theneedle 216 upwardly from the injection space 231, only the main plungermoves upwardly.

Stated differently, the shuttle 207 and main plunger 206 move upwardlyin conformity with the volume of the fuel flowing into the body 201 viathe volume regulating connector 209, and the main plunger 206 furthermoves upwardly in conformity with the volume of the fuel flowing intothe body 201 via the timing connector 208.

When the time for the particular cylinder of the engine to require fuelinjection comes, the cam 103 actuates the connecting rod 109 to moveupwardly and a portion of the rocker arm 111 corresponding to a head ofthe main plunger 206 begins to move downwardly. If the main plunger 206is disposed in an upper position under the influence of the volume ofthe fuel flowed into the body 201 as described hereinabove, then themain plunger 206 has a compressive force exerted thereon at an earlyperiod of the rotation of the engine.

The compressive force exerted on the main plunger 206 pressurizes thefuel in the pressurizing space 226 through the plunger 206. At thistime, the fuel communicated with the pressurizing space 226 has itspressure transmitted to the lower portion of the main plunger 206through the plunger 206, because the check valve 211 in the timingconnector 208 is closed and the overflow passage 223 is closed by theouter periphery of the shuttle 207. The fuel in the lower space 215 doesnot flow therefrom because the check valve 211 in the volume regulatingconnector 209 is closed but flows into the injection space 231 via thehigh-pressure vertical bore 220 and angling duct 219, with a result thatthe pressure in the injection space 231 acts on the 216. When thepressure acting on the needle 216 overcomes the biasing force of thespring 218 urging the needle 216 to move upwardly, the needle 216 movesupwardly and allows the fuel to be injected through the injecting port232 into the cylinder associated with the main pump 200. As the mainplunger 206 further moves downwardly and the fuel beneath the shuttle207 is injected and allows the shuttle 207 to move downwardly, theoverflow passage 223 which has been closed by the outer periphery of theshuttle 207 is brought into communication with the pressurizing space226. Further downward movement of the main plunger 206 allows the fuelin the pressurizing space 226 to be returned to the tank 101 through theoverflow passage 223 and discharge space 234, and through the overflowpipe 106 connected to the overflow connector 210 after opening the checkvalve 211 which is opened with a relatively low force.

The inflow of the fuel through the timing connector 208 into the body201 that takes place after the inflow of the fuel has taken placethrough the volume regulating connector 209 as described hereinaboveforces the shuttle 207 which remains stationary to move upwardly. Theforce that forces the main plunger 206 to move downwardly after theshuttle 207 has been moved upwardly causes the shuttle 207 to berestored to the position in which it remained stationary before. Thus,the fuel flowing into the body 201 through the volume regulatingconnector 209 as described hereinabove constitute the amount of the fuelthat is finally injected.

As described hereinabove, in the embodiment of the present invention,the inflow of the fuel into the body 201 of the main pump 200 takesplace in an orderly manner such that the fuel first flows to the portionof the body below the shuttle 207 and, after the overflow passage 223 isclosed by the outer periphery of the shuttle 207, only the main plunger206 is moved upwardly by the fluid.

This avoids the trouble that the fuel might flow to outside through theoverflow passage 223 if it is allowed to flow into the portion of thebody 201 above the shuttle 207 while the overflow passage 223 is stillopen.

The arrangement whereby the amount of the injected fuel and injectiontiming are decided by the single means offers the advantage that novariations occur between the cylinders in the amount of the injectedfuel and injection timing, making it possible to effect fuel injectioneconomically with a high degree of efficiency.

The two volumes of the fuel for deciding the amount of the injected fueland injection timing respectively are pressurized and distributed by thesingle pressurizing mechanism. This is conducive to increasedcompactness and reduced cost of the metering and distributing mechanism.

The supply of the two volumes of the fuel for deciding the amount of theinjected fuel and injection timing to each of the main pumps takes placein an orderly manner, so that the performance of the system isstabilized.

The two volumes of the fuel for deciding the amount of the injected fueland injection timing are metered under low pressure. This enables ametering device of high ability to withstand pressure to be obtained atlow cost.

The transfer of the fuel from the metering and distributing pump to eachof the main pumps is achieved under any pressure desired, so thatproduction of air bubbles can be avoided and the ability of the systemas a whole to withstand pressure can be set at a suitable level. Thisallows the fuel injection system to be produced readily at low cost.

In transferring the fuel from the metering and distributing pump to eachof the main pumps, it is possible to select the period of time for thetransfer with great latitude because the non-compression period of eachcylinder is substantially prolonged.

FIG. 7 shows, on an enlarged scale, portions of the roller shoe 8 androller 9 in contact with each other. The force exerted by the cam ring 3is transmitted to the plunger 2 through the roller 9 and roller shoe 8.At this time, a force of great magnitude is transmitted to a contactsurface (hemispherical surface) of the roller shoe 8 from the roller 9.Because particles of the materials of various parts of the pump producedby wear and contact tend to accumulate on the contact surface andincrease after a prolonged period of use, contact of the roller 9 withthe cam 3A of the cam ring 3 could become lopsided. In the embodimentshown and described hereinabove, a discharge groove 51 is formed at thecontact surface of the roller shoe 8 to facilitate discharge of theparticules accumulating as noted hereinabove. This allows the aforesaidtrouble to be avoided by keeping the contact surface of the roller shoe8 clean at all times and avoiding wear that might otherwise be caused onthe roller 9 and cam ring 3.

The arrangement whereby control of the amount of the injected fuel andinjection timing is effected in the vicinity of each cylinder of theengine before fuel injection finally takes place enables control to beeffected with a high degree of accuracy and precision because theinfluences exerted by a delay in transmission and waves of reflectioncan be minimized.

What is claimed is:
 1. A high-pressure fuel injection system for adiesel engine comprising:(a) a plurality of main pumps for injectingfuel each located at one of cylinders of the engine and formed with afuel injecting port, each said main pump for injecting fuel being formedwith a first injected fuel space filled with fuel to be injected, adischarge valve located in a path connecting said first injected fuelspace with said fuel injecting port, said discharge valve being openedwhen the fuel to be injected reaches a predetermined pressure level, afirst injection timing fuel space fluidly connected with said firstinjected fuel space through a movable shuttle and filled with injectiontiming fuel, and a plunger varying the volume of said first injectiontiming fuel space; (b) a metering and distributing pump formed withinjection fuel outputs and injection timing fuel outlets correspondingin number to the cylinders of the engine for discharging fuel in timedrelation to the rotation of the engine, said metering and distributingpump being formed with a second injected fuel space filled with the fuelto be injected and brought into communication with said injected fueloutlets in timed relation to the rotation of the engine, and a secondinjection timing fuel space filled with injection timing fuel fluidlycommunicated with said second injected fuel space through a movable freepiston and communicated with said injection timing fuel outlets in timedrelation to the rotation of the engine and equipped with pump means forcompressing the fuel in said second injection timing fuel space in timedrelation to the rotation of the engine; (c) a plurality of fuel meteringvalves for metering fuel flowing into said second injected fuel spaceand second injection timing fuel space respectively; (d) a plurality ofpipes for fluidly connecting said first injected fuel space and firstinjection timing fuel space of each said main pump for injecting fuelwith said injected fuel outlets and injection timing fuel outlets ofsaid metering and distributing pump respectively; and (e) a rocker armmechanism for driving the plunger of each said main pump for injectingfuel in timed relation to the rotation of the engine.
 2. A high-pressurefuel injection system for a diesel engine as claimed in claim 1, whereinsaid plurality of fuel metering valves each comprise a solenoid valve.3. A high-pressure fuel injection system for a diesel enginecomprising:(a) a metering and distributing pump formed with injectionfuel outlets and injection timing fuel outlets corresponding to thenumber of cylinders of the engine for respectively discharging injectionfuel and injecting timing fuel in synchronous relation to the rotationof the engine; (b) an injection fuel metering valve means and injectiontiming fuel metering valve means for respectively metering the fuel tobe injected and the fuel for defining fuel injection timing beforeintroduction into said metering and distributing pump; (c) a feed pumpfor supplying fuel to said injection fuel metering valves and saidinjection timing fuel metering valves; (d) a fuel injecting main pumplocated at each cylinder of the engine and formed with an injection fuelspace filled with fuel to be injected, an injection timing fuel spacefilled with fuel for defining fuel injection timing, and a fuelinjecting port, said fuel in said injection fuel space being dischargedthrough said fuel injection port by raising the pressure of the fuel insaid injection timing fuel space, and then transmitting the raisedpressure to the fuel in said injection fuel space; (e) pipe means forconnecting said injection fuel space and said injection timing fuelspace of each main pump with said corresponding injection fuel outletand injection timing fuel outlet of said metering and distributing pump;and (f) transmission means for controlling the fuel pressure in saidinjection timing fuel space of each main pump in synchronous relation tothe rotation of the engine.